Large aperture ratio telephoto lens system

ABSTRACT

A high-performance large aperture ratio telephoto lens system comprising a first lens group having positive refractive power, a second lens group having negative refractive power and a third lens unit having positive refractive power, the large aperture ratio telephoto lens system being arranged to fulfill the conditions shown below and to have the focal length about 200 mm to 300 mm and F number about F2. (1) 0.4f&lt;fI&lt;0.8f (2) 0.2f&lt;¦fII¦&lt;0.5f (3) 0.3f&lt;FIII&lt;0.8f.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a high-performance large aperture ratiotelephoto lens system with the focal length about 200 mm to 300 mm.

2. Description of the Prior Art

For known telephoto lens systems with the focal length about 200 mm to300 mm, the F number is about F4 in general. Even in case of bright lenssystems, the F number is about F2.8 at the best. However, one of recenttendencies of interchangeable lenses for cameras of 35 mm format is tomake the aperture ratio larger and a still brighter telephoto lenssystem is now being waited for. When, however, it is attempted to designa telephoto lens system with a large aperture ratio, it is difficult tofavourably correct chromatic aberration to be caused by the secondaryspectrum and to make both of spherical aberration and Petzval's sumsmall at the same time. Moreover, the lens system becomes large andlong. Therefore, as telephoto lens system of F2 class, there is only oneknown telephoto lens system which is disclosed in Japanese publishedunexamined patent application No. 134425/78. However, the abovementionedtelephoto lens system has a large telephoto ratio, i.e., about 1.23.

SUMMARY OF THE INVENTION

It is, therefore, a primary object of the present invention to provide alarge aperture ratio telephoto lens system which is extremely bright,i.e., F2.0, in spite of the fact that the focal length thereof is long,i.e., 200 mm to 300 mm, and which shows high performance and has smalltelephoto ratio of 1.08 or less.

The telephoto lens system according to the present invention comprises afirst lens group I having positive refractive power as a whole, a secondlens group II having negative refractive power as a whole, and a thirdlens unit III having positive refractive power as a whole, and isarranged to fulfill the conditions (1), (2) and (3) shown below:

(1) 0.4f<f_(I) <0.8f

(2) 0.2f<|f_(II) |<0.5f

(3) 0.3f<f_(III) <0.8f

where, reference symbol f_(I) represents the focal length of the firstlens group I, reference symbol f_(II) represents the focal length of thesecond lens group II, reference symbol f_(III) represents the focallength of the third lens unit III, and reference symbol f represents thefocal length of the lens system as a whole.

Besides, respective lens groups constituting the telephoto lens systemaccording to the present invention are composed as described below. Thatis, the first lens group I comprises a first lens component havingpositive refractive power, a second lens component having negativerefractive power, a third lens component having positive refractivepower, and a fourth lens component which is a positive meniscus lensconvex toward the object side or a biconvex lens. The second lens groupII comprises a fifth lens component having negative refractive power anda sixth lens component having negative refractive power. The third lensunit III comprises a senventh lens component having positive refractivepower.

Large aperture ratio lens systems such as Gauss type lens system havefundamental lens configuration that the lens system comprises aconverging lens group, a diverging lens group and a converging lensgroup in the order from the object side toward the image side. The lenssystem according to the present invention is also arranged to have suchlens configuration as to have power distribution similar to that ofGauss type lens system. Besides, in order to make the telephoto ratiosmall, i.e., to arrange so that the principal point on the image side ofthe lens system comes to a position as forward as possible, the secondlens group II is arranged in a position spaced from the first lens groupI so as to reserve some airspace between the first and second lensgroups and, moreover, the total focal length of the second lens group IIis made short so that the second lens group has strong diverging effect.

The condition (2) defines the focal length of the above-mentioned secondlens group. If f_(II) becomes larger than the upper limit of thecondition (2), it becomes difficult to make the telephoto ratio small.When f_(II) becomes smaller than the lower limit of the condition (2),it is advantageous for making the telephoto ratio small. However, itbecomes difficult to favourably correct all of spherical aberration,coma flare, distortion and chromatic aberration due to the secondaryspectrum at the same time.

To make the telephoto ratio small, it is necessary to let the first lensgroup I have strong converging effect by making its focal length short.The condition (1) defines the focal length of the first lens group. Iff_(I) becomes larger than the upper limit of the condition (1), itbecomes difficult to make the telephoto ratio small. When f_(I) becomessmaller than the lower limit of the condition (1) , it is advantageousfor making the telephoto ratio small. However, it becomes difficult tofavourably correct all of spherical aberration, coma flare, distortionand secondary spectrum at the same time. Especially, the secondaryspectrum is largely caused by the first lens group I and is enlarged bythe other lens groups.

When the fourth lens component in the first lens group I is arranged ina position spaced from the other lens components, i.e., the first,second and third lens components, by providing some airspace between thethird lens component and fourth lens component, it is possible to makethe total weight of the lens system light. If, however, the fourth lenscomponent is arranged in a position too near the image side, the focallength f_(I) of the first lens group becomes short compared with thetelephoto ratio and this is not desirable for correction of aberrations.

The condition (3) defines the focal length of the third lens unit III.If f_(III) becomes larger than the upper limit of the condition (3),positive distortion occurs considerably. If f_(III) becomes smaller thanthe lower limit of the condition (3), it becomes difficult to make thetelephoto ratio small.

When the second lens component is arranged as a biconcave lens or thelike which is convenient for the manufacture, it becomes sometimesdifficult to correct chromatic aberration. In such case, it is possibleto favourably correct both of longitudinal chromatic aberration andlateral chromatic aberration at the same time when both of the fifthlens component and seventh component are respectively arranged ascemented doublets which fulfill the conditions (4) and (5) shown below:

(4) ν_(5n) -ν_(5p) >10

(5) ν_(7p) -ν_(7n) >15

where, reference symbols ν_(5p) and ν_(5n) respectively represent Abbe'snumbers of the positive lens and negative lens constituting the fifthlens component, and reference symbols ν_(7p) and ν_(7n) respectivelyrepresent Abbe's numbers of the positive lens and negative lensconstituting the seventh lens component.

That is, when the second lens component is arranged as a biconcave lens,lateral chromatic aberration for the ray of short wavelength caused bythis lens component becomes a negative value with a large absolute valueand longitudinal chromatic aberration for the ray of short wavelengthcaused by this lens component becomes a large positive value. Thisproblem can be solved when the fifth lens component and seventh lenscomponent are respectively arranged as cemented doublets each consistingof a positive lens and a negative lens and it is arranged as follows.That is, the difference between Abbe's numbers ν_(p) and ν_(n) of thepositive lens and negative lens constituting the fifth cemented lenscomponent is made large as defined by the condition (4) and thedifference between Abbe's numbers ν_(p) and ν_(n) of the positive lensand negative lens constituting the seventh lens component is also madelarge as defined by the condition (5) so that lateral chromaticaberration caused by each of these cemented doublets becomes a positivevalue and longitudinal chromatic aberration caused by each of thesecemented doublets becomes a negative value in order to thereby offsetchromatic aberration caused by the above-mentioned diconcave lens. Thus,it is possible to favourably correct chromatic aberration of the lenssystem as a whole.

Now, when the second lens component and third lens component in thefirst converging lens group (the first lens group I) are interchanged sothat the second lens component becomes a positive lens and the thirdlens component becomes a negative lens, it is advantageous for makingthe telephoto ratio small.

Besides, it is possible to make Petzval's sum still smaller byfavourably correcting lateral chromatic aberration when the seventh lenscomponent is arranged so that it comprises a positive lens, negativelens and positive lens in the order from the object side, these lensesare arranged as single lenses separate from each other or two of themare arranged to form a cemented doublet, and it is so arranged thatAbbe's numbers ν_(p) of the above-mentioned positive lenses and Abbe'snumber ν_(n) of the above-mentioned negative lens fulfill the ralationexpressed by the condition (6) shown below and refractive indices n_(p)of the above-mentioned positive lenses and refractive index n_(n) of theabove-mentioned negative lens fulfill the relation expressed by thecondition (7) shown below:

(6) ν_(7p) -ν_(8n) >10, ν_(9p) -ν_(8n) >10

(7) n_(7p) -n_(8n) >0.1, n_(9p) -n_(8n) >0.1

where, reference symbol ν_(7p) represents Abbe's number of the positivelens arranged on the object side in the seventh lens component,rererence symbol ν_(8n) represents Abbe's number of the negative lens inthe seventh lens component, reference symbol ν_(9p) represents Abbe'snumber of the positive lens arranged on the image side in the seventhlens component, reference symbol n_(7p) represents the refractive indexof the positive lens arranged on the object side in the seventh lenscomponent, reference symbol n_(8n) represents the refractive index ofthe negative lens in the seventh lens component, and reference symboln_(9p) represents the refractive index of the positive lens arranged onthe image side in the seventh lens component.

It is possible to correct lateral chromatic aberration effectively whenthe seventh lens component is arranged as described in the above, glassmaterials with small dispersion (large Abbe's numbers) are used for thepositive lenses therein glass material with large dispersion (smallAbbe's number) is used for the negative lens therein, and it is soarranged that the above-mentioned condition (6) is fulfilled. When theseventh lens component is arranged as described in the above and, at thesame time, the fifth lens component is arranged as a cemented doubletwhich fulfills the condition (4) as described before, it is possible tocorrect lateral chromatic aberration more favourably. Besides, whenrefractive indices of the positive lenses in the seventh lens componentare made high and refractive index of the negative lens in the seventhlens component is made low so that the above-mentioned condition (7) isfulfilled, it is possible to make Petzval's sum small. If the condition(6) and/or condition (7) is not fulfilled, the above-mentionedaberrations cannot be corrected favourably and, therefore, theabove-mentioned arrangement of the seventh lens component loses itssignificance.

BRIEF DESCRIPTION OF THE DRAWINGS

FIGS. 1 through 5 respectively show sectional views of Embodiments 1through 5 of the large aperture ratio telephoto lens system according tothe present invention; and

FIGS. 6 through 10 respectively show graphs illustrating aberrationcurves of Embodiments 1 through 5 of the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Now, preferred embodiments of the large aperture ratio telephoto lenssystem according to the present invention described so far are shownbelow.

    ______________________________________                                        Embodiment 1                                                                  ______________________________________                                        r.sub.1 = 98.7017                                                             d.sub.1 = 6.4000                                                                             n.sub.1 = 1.49700                                                                          ν.sub.1 = 81.61                                r.sub.2 = -886.0035                                                           d.sub.2 = 0.7132                                                              r.sub.3 = 68.5465                                                             d.sub.3 = 3.2000                                                                             n.sub.2 = 1.71736                                                                          ν.sub.2 = 29.51                                r.sub.4 = 42.7293                                                             d.sub.4 = 0.4000                                                              r.sub.5 = 42.4331                                                             d.sub.5 = 8.0000                                                                             n.sub.3 = 1.49700                                                                          ν.sub.3 = 81.61                                r.sub.6 = 123.1902                                                            d.sub.6 = 0.7901                                                              r.sub.7 = 36.4921                                                             d.sub.7 = 5.2000                                                                             n.sub.4 = 1.61405                                                                          ν.sub.4 = 54.95                                r.sub.8 = 67.8212                                                             d.sub.8 = 27.2000                                                             r.sub.9 = 275.6826                                                            d.sub.9 = 2.4000                                                                             n.sub.5 = 1.68893                                                                          ν.sub.5 = 31.08                                r.sub.10 = 18.6995                                                            d.sub.10 = 8.6188                                                             r.sub.11 = -28.3202                                                           d.sub.11 = 2.0101                                                                            n.sub.6 = 1.69350                                                                          ν.sub.6 = 53.23                                r.sub.12 = -43.8107                                                           d.sub.12 = 2.0000                                                             r.sub.13 = 55.8572                                                            d.sub.13 = 3.2000                                                                            n.sub.7 = 1.79952                                                                          ν.sub.7 = 42.24                                r.sub.14 = -50.9340                                                           f = 100, 2ω = 10.2°                                              f.sub.I = 67.1, f.sub.II = -22.6, f.sub.III = 33.8                            telephoto ratio = 1.07                                                        ______________________________________                                    

    ______________________________________                                        Embodiment 2                                                                  ______________________________________                                        r.sub.1 = 62.7870                                                             d.sub.1 = 6.3968                                                                             n.sub.1 = 1.49700                                                                          ν.sub.1 = 81.61                                r.sub.2 = 254.7626                                                            d.sub.2 = 0.7094                                                              r.sub.3 = 64.3102                                                             d.sub.3 = 3.1946                                                                             n.sub.2 = 1.68893                                                                          ν.sub.2 = 31.08                                r.sub.4 = 44.3243                                                             d.sub.4 = 2.3998                                                              r.sub.5 = 39.0266                                                             d.sub.5 = 7.9950                                                                             n.sub.3 = 1.49700                                                                          ν.sub.3 = 81.61                                r.sub.6 = 163.6161                                                            d.sub.6 = 18.0051                                                             r.sub.7 = 24.8172                                                             d.sub.7 = 5.2013                                                                             n.sub.4 = 1.55963                                                                          ν.sub.4 = 61.17                                r.sub.8 = 57.6824                                                             d.sub.8 = 6.0029                                                              r.sub.9 = 224.0323                                                            d.sub.9 = 1.9998                                                                             n.sub.5 = 1.63980                                                                          ν.sub.5 = 34.48                                r.sub.10 = 17.1727                                                            d.sub. 10 = 6.6011                                                            r.sub.11 = -35.4438                                                           d.sub.11 = 2.0028                                                                            n.sub.6 = 1.55963                                                                          ν.sub.6 = 61.17                                r.sub.12 = -86.1376                                                           d.sub.12 = 9.2005                                                             r.sub.13 = 81.8924                                                            d.sub.13 = 3.2006                                                                            n.sub.7 = 1.79952                                                                          ν.sub.7 = 42.24                                r.sub.14 = -68.0100                                                           f = 100, 2ω = 10.2°                                              f.sub.I = 49.2, f.sub.II = -22.1, f.sub.III = 46.9                            telephoto ratio = 1.08                                                        ______________________________________                                    

    ______________________________________                                        Embodiment 3                                                                  ______________________________________                                        r.sub.1 = 57.0426                                                             d.sub.1 = 8.0000                                                                             n.sub.1 = 1.49700                                                                          ν.sub.1 = 81.61                                r.sub.2 = -1284.1181                                                          d.sub.2 = 2.4000                                                              r.sub.3 = -144.2420                                                           d.sub.3 = 3.2000                                                                             n.sub.2 = 1.68893                                                                          ν.sub.2 = 31.08                                r.sub.4 = 162.4364                                                            d.sub.4 = 0.2000                                                              r.sub.5 = 45.0574                                                             d.sub.5 = 8.8000                                                                             n.sub.3 = 1.49700                                                                          ν.sub.3 = 81.61                                r.sub.6 = -521.7284                                                           d.sub.6 = 12.8000                                                             r.sub.7 = 47.3799                                                             d.sub.7 = 4.0000                                                                             n.sub.4 = 1.63930                                                                          ν.sub.4 = 44.88                                r.sub.8 = 109.9734                                                            d.sub.8 = 10.0000                                                             r.sub.9 = -82.8030                                                            d.sub.9 = 1.6000                                                                             n.sub.5 = 1.51633                                                                          ν.sub.5 = 64.15                                r.sub.10  = 37.0546                                                           d.sub.10 = 3.2000                                                                            n.sub.6 = 1.54072                                                                          ν.sub.6 = 47.20                                r.sub.11 = 5892.8215                                                          d.sub.11 = 4.0000                                                             r.sub.12 = -93.1116                                                           d.sub.12 = 2.0000                                                                            n.sub.7 = 1.51633                                                                          ν.sub.7 = 64.15                                r.sub.13 = 19.8771                                                            d.sub.13 = 8.0000                                                             r.sub.14 = 36.7676                                                            d.sub.14 = 3.2000                                                                            n.sub.8 = 1.69680                                                                          ν.sub.8 = 55.52                                r.sub.15 = -36.1124                                                           d.sub.15 = 1.6000                                                                            n.sub.9 = 1.63980                                                                          ν.sub.9 = 34.48                                r.sub.16 = 1648.2317                                                          f = 100, 2ω = 10.2°                                              f.sub.I = 57.8, f.sub.II = -26.0, f.sub.III = 49.4                            telephoto ratio = 1.04                                                        ______________________________________                                    

    ______________________________________                                        Embodiment 4                                                                  ______________________________________                                        r.sub.1 = 113.9323                                                            d.sub.1 = 3.9981                                                                              n.sub.1 = 1.60311                                                                          ν.sub.1 = 60.70                               r.sub.2 = 605.7931                                                            d.sub.2 = 0.1995                                                              r.sub.3 = 59.2482                                                             d.sub.3 = 7.9962                                                                              n.sub.2 = 1.49700                                                                          ν.sub.2 = 81.61                               r.sub.4 = 9999.0000                                                           d.sub.4 = 0.9995                                                              r.sub.5 = -541.1335                                                           d.sub.5 = 3.1993                                                                              n.sub.3 = 1.68893                                                                          ν.sub.3 = 31.08                               r.sub.6 = 95.1017                                                             d.sub.6 = 0.1999                                                              r.sub.7 = 40.4668                                                             d.sub.7 = 7.9962                                                                              n.sub.4 = 1.49700                                                                          ν.sub.4 = 81.61                               r.sub.8 = 549.6163                                                            d.sub.8 = 22.7891                                                             r.sub.9 = -70.8441                                                            d.sub.9 = 3.1985                                                                              n.sub.5 = 1.74950                                                                          ν.sub.5 = 35.27                               r.sub.10 =  -34.7538                                                          d.sub.10 = 1.9990                                                                             n.sub.6 = 1.55963                                                                          ν.sub.6 = 61.17                               r.sub.11 = 28.3565                                                            d.sub.11 = 3.9981                                                             r.sub.12 = 54.5868                                                            d.sub.12 = 1.9990                                                                             n.sub.7 = 1.55963                                                                          ν.sub.7 = 61.17                               r.sub.13 = 23.4440                                                            d.sub.13 = 6.3970                                                             r.sub.14 = 32.5655                                                            d.sub.14 = 3.9981                                                                             n.sub.8 = 1.71300                                                                          ν.sub.8 = 53.84                               r.sub.15 = -36.5538                                                           d.sub.15 = 1.9990                                                                             n.sub.9 = 1.71736                                                                          ν.sub.9 = 29.51                               r.sub.16 = -122.9378                                                          f = 100, 2ω = 10.2°                                              f.sub.I = 66.0, f.sub.II = -24.4, f.sub.III = 36.8                            telephoto ratio = 1.08                                                        ______________________________________                                    

    ______________________________________                                        Embodiment 5                                                                  ______________________________________                                        r.sub.1 = 75.4815                                                             d.sub.1 = 6.0000                                                                              n.sub.1 = 1.60311                                                                          ν.sub.1 = 60.70                               r.sub.2 = 449.9478                                                            d.sub.2 = 0.1948                                                              r.sub.3 = 46.1480                                                             d.sub.3 = 7.8000                                                                              n.sub.2 = 1.49700                                                                          ν.sub.2 = 81.61                               r.sub.4 = -863.7624                                                           d.sub.4 = 2.8000                                                              r.sub.5 = -256.0298                                                           d.sub.5 = 3.2000                                                                              n.sub.3 = 1.68893                                                                          ν.sub.3 = 31.08                               r.sub.6 = 66.0450                                                             d.sub.6 = 2.3992                                                              r.sub.7 = 59.0703                                                             d.sub.7 = 5.2000                                                                              n.sub.4 = 1.49700                                                                          ν.sub.4 = 81.61                               r.sub.8 = -275.9274                                                           d.sub.8 = 12.7999                                                             r.sub.9 = -107.6214                                                           d.sub.9 = 2.8000                                                                              n.sub.5 = 1.68893                                                                          ν.sub.5 = 31.08                               r.sub.10  = -40.2998                                                          d.sub.10 = 2.4000                                                                             n.sub.6 = 1.51633                                                                          ν.sub.6 = 64.15                               r.sub.11 = 105.0318                                                           d.sub.11 = 2.8000                                                             r.sub.12 = 278.4266                                                           d.sub.12 = 2.0000                                                                             n.sub.7 = 1.51633                                                                          ν.sub.7 = 64.15                               r.sub.13 = 32.7893                                                            d.sub.13 = 15.2000                                                            r.sub.14 = 33.8541                                                            d.sub.14 = 3.2000                                                                             n.sub.8 = 1.73400                                                                          ν.sub.8 = 51.49                               r.sub.15 = -103.6635                                                          d.sub.15 = 1.2043                                                             r.sub.16 = -58.1818                                                           d.sub.16 = 1.2000                                                                             n.sub.9 = 1.58144                                                                          ν.sub.9 = 40.75                               r.sub.17 = 26.2954                                                            d.sub.17 = 1.2000                                                             r.sub.18 = 45.2421                                                            d.sub.18 = 2.8000                                                                             n.sub.10 = 1.73400                                                                         ν.sub.10 = 51.49                              r.sub.19 = 698.4416                                                           f = 100, 2ω = 10.2°                                              f.sub. I = 66.8, f.sub.II = -46.5, f.sub.III = 77.2                           telephoto ratio = 1.06                                                        ______________________________________                                    

In embodiments shown in the above, reference symbols r₁, r₂, . . .respectively represent radii of curvature of respective lens surfaces,reference symbols d₁, d₂, . . . respectively represent thicknesses ofrespective lenses and airspaces between respective lenses, referencesymbols n₁, n₂, . . . respectively represent refractive indices ofrespective lenses, and reference symbols ν₁, ν₂, . . . respectivelyrepresent Abbe's numbers of respective lenses.

Out of embodiments shown in the above, Embodiment 1 has lensconfiguration shown in FIG. 1 and its aberration curves are shown inFIG. 6. Embodiment 2 has lens configuration shown in FIG. 2, i.e., thefourth lens component is spaced from the first through third lenscomponents, and its aberration curves are shown in FIG. 7. Embodiment 3has lens configuration shown in FIG. 3, i.e., the second lens componentis arranged as a biconcave lens, the fourth lens component is spacedfrom the third lens component toward the image side, and both of thefifth and seventh lens components are arranged as cemented doublets.Aberration curves of Embodiment 3 are shown in FIG. 8. Embodiment 4 haslens configuration shown in FIG. 4, i.e., the second lens component isarranged as a positive lens, the third lens component is arranged as anegative lens, and both of the fifth and seventh lens comonents arearranged as cemented doublets. Aberration curves of Embodiment 4 areshown in FIG. 9. Embodiment 5 has lens configuration shown in FIG. 5,i.e., the second lens component is arranged as a positive lens, thethird lens component is arranged as a negative lens, the fifth lenscomponent is arranged as a cemented doublet, and the seventh lenscomponent is arranged so that it comprises a positive lens, negativelens and positive lens. Aberration curves of Embodiment 5 are shown inFIG. 10.

I claim:
 1. A larger aperture ratio telephoto lens system consisting ofa first lens group having four lenses and having positive refractivepower as a whole, a second lens group having two negative lenses andhaving negative refractive power as a whole, and a third lens unithaving a single lens, said large aperture ratio telephoto lens systembeing so adapted as to satisfy the conditions (1) through (3) shownbelow:(1) 0.4f<f_(I) <0.8f (2) 0.2f<|f_(II) |<0.5f (3) 0.3f<f_(III)<0.8fwherein reference symbol f represents the focal length of the lenssystem as a whole, and reference symbols f_(I), f_(II) and f_(III)respectively represent focal lengths of the first and second lens groupsand the third lens unit.
 2. A large aperture ratio telephoto lens systemaccording to claim 1 wherein said first lens group comprises a positivelens, a negative meniscus lens having a convex surface on the objectside, a positive meniscus lens having a convex surface on the objectside and a positive meniscus lens having a convex surface on the objectside, and said second lens group comprises two negative meniscus lenseshaving concave surfaces facing each other.
 3. A large aperture ratiotelephoto lens system according to claim 2, in which said large apertureratio telephoto lens system has the following numerical data:

    ______________________________________                                        r.sub.1 = 98.7017                                                             d.sub.1 = 6.4000                                                                             n.sub.1 = 1.49700                                                                          ν.sub.1 = 81.61                                r.sub.2 = -886.0035                                                           d.sub.2 = 0.7132                                                              r.sub.3 = 68.5465                                                             d.sub.3 = 3.2000                                                                             n.sub.2 = 1.71736                                                                          ν.sub.2 = 29.51                                r.sub.4 = 42.7293                                                             d.sub.4 = 0.4000                                                              r.sub.5 = 42.4331                                                             d.sub.5 = 8.0000                                                                             n.sub.3 = 1.49700                                                                          ν.sub.3 = 81.61                                r.sub.6 = 123.1902                                                            d.sub.6 = 0.7901                                                              r.sub.7 = 36.4921                                                             d.sub.7 = 5.2000                                                                             n.sub.4 = 1.61405                                                                          ν.sub.4 = 54.95                                r.sub.8 = 67.8212                                                             d.sub.8 = 27.2000                                                             r.sub.9 = 275.6826                                                            d.sub.9 = 2.4000                                                                             n.sub.5 = 1.68893                                                                          ν.sub.5 = 31.08                                r.sub.10 = 18.6995                                                            d.sub.10  = 8.6188                                                            r.sub.11 = -28.3202                                                           d.sub.11 = 2.0101                                                                            n.sub.6 = 1.69350                                                                          ν.sub.6 = 53.23                                r.sub.12 = -43.8107                                                           d.sub.12 = 2.0000                                                             r.sub.13 = 55.8572                                                            d.sub.13 = 3.2000                                                                            n.sub.7 = 1.79952                                                                          ν.sub.7 = 42.24                                r.sub.14 = -50.9340                                                           f = 100, 2ω = 10.2°                                              f.sub.I = 67.1, f.sub.II = -22.6, f.sub.III = 33.8                            telephoto ratio = 1.07                                                        ______________________________________                                    

wherein reference symbols r₁ through r₁₄ respectively represent radii ofcurvature of respective lens surfaces, reference symbols d₁ through d₁₃respectively represent thicknesses of respective lenses and airspacesbetween respective lenses, reference symbols n₁ through n₇ respectivelyrepresent refractive indices of respective lenses, reference symbols, ν₁through ν₇ respectively represent Abbe's numbers of respective lenses,and reference symbol 2ω represents the field angle.
 4. A large apertureratio telephoto lens system according to claim 2, in which said largeaperture ratio telephoto lens system has the following numerical data:

    ______________________________________                                        r.sub.1 = 62.7870                                                             d.sub.1 = 6.3968                                                                             n.sub.1 = 1.49700                                                                          ν.sub.1 = 81.61                                r.sub.2 = 254.7626                                                            d.sub.2 = 0.7094                                                              r.sub.3 = 64.3102                                                             d.sub.3 = 3.1946                                                                             n.sub.2 = 1.68893                                                                          ν.sub.2 = 31.08                                r.sub.4 = 44.3243                                                             d.sub.4 = 2.3998                                                              r.sub.5 = 39.0266                                                             d.sub.5 = 7.9950                                                                             n.sub.3 = 1.49700                                                                          ν.sub.3 = 81.61                                r.sub.6 = 163.6161                                                            d.sub.6 = 18.0051                                                             r.sub.7 = 24.8172                                                             d.sub.7 = 5.2013                                                                             n.sub.4 = 1.55963                                                                          ν.sub.4 = 61.17                                r.sub.8 = 57.6824                                                             d.sub.8 = 6.0029                                                              r.sub.9 = 224.0323                                                            d.sub.9 = 1.9998                                                                             n.sub.5 = 1.63980                                                                          ν.sub.5 = 34.48                                r.sub.10 = 17.1727                                                            d.sub.10 =  6.6011                                                            r.sub.11 = -35.4438                                                           d.sub.11 = 2.0028                                                                            n.sub.6 = 1.55963                                                                          ν.sub.6 = 61.17                                r.sub.12 = -86.1376                                                           d.sub.12 = 9.2005                                                             r.sub.13 = 81.8924                                                            d.sub.13 = 3.2006                                                                            n.sub.7 = 1.79952                                                                          ν.sub.7 = 42.24                                r.sub.14 = -68.0100                                                           f = 100, 2ω = 10.2°                                              f.sub.I = 49.2, f.sub.II = -22.1, f.sub.III = 46.9                            telephoto ratio = 1.08                                                        ______________________________________                                    

wherein reference symbols r₁ through r₁₄ respectively represent radii ofcurvature of respective lens surfaces, reference symbols d₁ through d₁₃respectively represent thicknesses of respective lenses and airspacesbetween respective lenses, reference symbols n₁ through n₇ respectivelyrepresent refractive indices of respective lenses, reference symbols ν₁through ν₇ respectively represent Abbe's numbers of respective lenses,and reference symbol 2ω represents the field angle.
 5. A large apertureratio telephoto lens system comprising a first lens group comprising apositive lens, a negative lens, a positive lens and a positive lens, asecond lens group comprising a negative cemented doublet and positivecemented doublet, said large aperture ratio telephoto lens system havingthe following numerical data:

    ______________________________________                                        r.sub.1 = 57.0426                                                             d.sub.1 = 8.0000                                                                             n.sub.1 = 1.49700                                                                          ν.sub.1 = 81.61                                r.sub.2 = -1284.1181                                                          d.sub.2 = 2.4000                                                              r.sub.3 = -144.2420                                                           d.sub.3 = 3.2000                                                                             n.sub.2 = 1.68893                                                                          ν.sub.2 = 31.08                                r.sub.4 = 162.4364                                                            d.sub.4 = 0.2000                                                              r.sub.5 = 45.0574                                                             d.sub.5 = 8.8000                                                                             n.sub.3 = 1.49700                                                                          ν.sub.3 = 81.61                                r.sub.6 = -521.7284                                                           d.sub.6 = 12.8000                                                             r.sub.7 = 47.2799                                                             d.sub.7 = 4.0000                                                                             n.sub.4 = 1.63930                                                                          ν.sub.4 = 44.88                                r.sub.8 = 109.9734                                                            d.sub.8 = 10.0000                                                             r.sub.9 = -82.8030                                                            d.sub.9 = 1.6000                                                                             n.sub.5 = 1.51633                                                                          ν.sub.5 = 64.15                                r.sub.10 = 37.0546                                                            d.sub.10 = 3.2000                                                                            n.sub.6 = 1.54072                                                                          ν.sub.6 = 47.20                                r.sub.11 = 5892.8215                                                          d.sub.11 = 4.0000                                                             r.sub.12 = -93.1116                                                           d.sub.12 = 2.0000                                                                            n.sub.7 = 1.51633                                                                          ν.sub.7 = 64.15                                r.sub.13 = 19.8771                                                            d.sub.13 = 8.0000                                                             r.sub.14 = 36.7676                                                            d.sub.14 = 3.2000                                                                            n.sub.8 = 1.69680                                                                          ν.sub.8 = 55.52                                r.sub.15 = -36.1124                                                           d.sub.15 = 1.6000                                                                            n.sub.9 = 1.63980                                                                          ν.sub.9 = 34.48                                r.sub.16 = 1648.2317                                                          f = 100, 2ω = 10.2°                                              f.sub.I = 57.8, f.sub.II = -26.0, f.sub.III = 49.4                            telephoto ratio = 1.04                                                        ______________________________________                                    

wherein reference symbols r₁ through r₁₆ respectively represent radii ofcurvature of respective lens surfaces, reference symbols d₁ through d₁₅respectively represent thicknesses of respective lenses and airspacesbetween respective lenses, reference symbols n₁ through n₉ respectivelyrepresent refractive indices of respective lenses, reference symbols ν₁through ν₉ respectively represent Abbe's numbers of respective lenses,and reference symbol 2ω represents the field angle.
 6. A larger apertureratio telephoto lens system comprising a positive lens, a positive lens,a negative lens and a positive lens, a second lens group comprising anegative cemented doublet and a negative lens, and a third lens unitcomprising a positive cemented doublet, said large aperture ratiotelephoto lens system having the following numerical data:

    ______________________________________                                        r.sub.1 = 113.9323                                                            d.sub.1 = 3.9981                                                                              n.sub.1 = 1.60311                                                                          ν.sub.1 = 60.70                               r.sub.2 = 605.7931                                                            d.sub.2 = 0.1995                                                              r.sub.3 = 59.2482                                                             d.sub.3 = 7.9962                                                                              n.sub.2 = 1.49700                                                                          ν.sub.2 = 81.61                               r.sub.4 = 9999.0000                                                           d.sub.4 = 0.9995                                                              r.sub.5 = -541.1335                                                           d.sub.5 = 3.1993                                                                              n.sub.3 = 1.68893                                                                          ν.sub.3 = 31.08                               r.sub.6 = 95.1017                                                             d.sub.6 = 0.1999                                                              r.sub.7 = 40.4668                                                             d.sub.7 = 7.9962                                                                              n.sub.4 = 1.49700                                                                          ν.sub.4 = 81.61                               r.sub.8 = 549.6163                                                            d.sub.8 = 22.7891                                                             r.sub.9 = -70.8441                                                            d.sub.9 = 3.1985                                                                              n.sub.5 = 1.74950                                                                          ν.sub.5 = 35.27                               r.sub.10 = -34.7538                                                           d.sub. 10 = 1.9990                                                                            n.sub.6 = 1.55963                                                                          ν.sub.6 = 61.17                               r.sub.11 = 28.3565                                                            d.sub.11 = 3.9981                                                             r.sub.12 = 54.5868                                                            d.sub.12 = 1.9990                                                                             n.sub.7 = 1.55963                                                                          ν.sub.7 = 61.17                               r.sub.13 = 23.4440                                                            d.sub.13 = 6.3970                                                             r.sub.14 = 32.5655                                                            d.sub.14 = 3.9981                                                                             n.sub.8 = 1.71300                                                                          ν.sub.8 = 53.84                               r.sub.15 = -36.5538                                                           d.sub.15 = 1.9990                                                                             n.sub.9 = 1.71736                                                                          ν.sub.9 = 29.51                               r.sub.16 = -122.9378                                                          f = 100, 2ω = 10.2°                                              f.sub.I = 66.0, f.sub.II = -24.4, f.sub.III = 36.8                            telephoto ratio = 1.08                                                        ______________________________________                                    

wherein reference symbols r₁ through r₁₆ respectively represent radii ofcurvature of respective lens surfaces, reference symbols d₁ through d₁₅respectively represent thicknesses of respective lenses and airspacesbetween respective lenses, reference symbols n₁ through n₉ respectivelyrepresent refractive indices of respective lenses, reference symbols ν₁through ν₉ respectively represent Abbe's numbers of respective lenses,and reference symbol 2ω represents the field angle.
 7. A large apertureratio telephoto lens system comprising a first lens group comprising apositive lens, a positive lens, a negative lens and a positive lens, asecond lens group comprising a negative cemented doublet and a negativelens and a third lens unit comprising a positive lens, a negative lensand a positive lens, said larger aperture ratio telephoto lens systemhaving the following numerical data:

    ______________________________________                                        r.sub.1 = 75.4815                                                             d.sub.1 = 6.0000                                                                              n.sub.1 = 1.60311                                                                          ν.sub.1 = 60.70                               r.sub.2 = 449,9478                                                            d.sub.2 = 0.1948                                                              r.sub.3 = 46.1480                                                             d.sub.3 = 7.8000                                                                              n.sub.2 = 1.49700                                                                          ν.sub.2 = 81.61                               r.sub.4 = -863.7624                                                           d.sub.4 = 2.8000                                                              r.sub.5 = -256.0298                                                           d.sub.5 = 3.2000                                                                              n.sub.3 = 1.68893                                                                          ν.sub.3 = 31.08                               r.sub.6 = 66.0450                                                             d.sub.6 = 2.3992                                                              r.sub.7 = 59.0703                                                             d.sub.7 = 5.2000                                                                              n.sub.4 = 1.49700                                                                          ν.sub.4 = 81.61                               r.sub.8 = -275.9274                                                           d.sub.8 = 12.7999                                                             r.sub.9 = -107.6214                                                           d.sub.9 = 2.8000                                                                              n.sub.5 = 1.68893                                                                          ν.sub.5 = 31.08                               r.sub.10 = -40.2998                                                           d.sub.10 = 2.4000                                                                             n.sub.6 = 1.51633                                                                          ν.sub.6 = 64.15                               r.sub.11 = 105.0318                                                           d.sub.11 = 2.8000                                                             r.sub.12 = 278.4266                                                           d.sub.12 = 2.0000                                                                             n.sub.7 = 1.51633                                                                          ν.sub.7 = 64.15                               r.sub.13 = 32.7893                                                            d.sub.13 = 15.2000                                                            r.sub.14 = 33.8541                                                            d.sub.14 = 3.2000                                                                             n.sub.8 = 1.73400                                                                          ν.sub.8 = 51.49                               r.sub.15 = -103.6635                                                          d.sub.15 = 1.2043                                                             r.sub.16 = -58.1818                                                           d.sub.16 = 1.2000                                                                             n.sub.9 = 1.58144                                                                          ν.sub.9 = 40.75                               r.sub.17 = 26.2954                                                            d.sub.17 = 1.2000                                                             r.sub.18 = 45.2421                                                            d.sub.18 = 2.8000                                                                             n.sub.10 = 1.73400                                                                         ν.sub.10 = 51.49                              r.sub.19 = 698.4416                                                           f = 100, 2ω = 10.2°                                              f.sub.I =  66.8, f.sub.II = -46.5, f.sub.III = 77.2                           telephoto ratio = 1.06                                                        ______________________________________                                    

wherein reference symbols r₁ through r₁₉ respectively represent radii ofcurvature of respective lens surfaces, reference symbols d₁ through d₁₈respectively represent thicknesses of respective lenses and airspacesbetween respective lenses, reference symbols n₁ through n₁₀ respectivelyrepresent refractive indices of respective lenses, reference symbols ν₁through ν₁₀ respectively represent Abbe's numbers of respective lenses,and reference symbol 2ω represents the field angle.